1. Field of the Invention
This invention relates to novel multi-layered film preparations and processes for the production thereof. More specifically, this invention relates to the multi-layered film preparations obtained by the combination of water soluble bases and water insoluble bases, characterized by that the prostaglandin or prostaglandins contained therein exhibit the desired long-lasting release patterns, further fully satisfying the purposes expected on prostaglandins aiming to lend themselves to uses as drug preparations which have high biological availability and are effective and safe, as well as the processes for the production thereof.
2. Description of the Prior Art
Various techniques for releasing drugs for an extended period of time have heretofore been reported in the literature. For instance, there are known coating methods to maintain release for an extended period of time as found mainly in oral tablets, intravaginally devices, drug release devices utilizing the osmotic pressure and despensers utilizing semipermeable membranes or porous membranes etc. In more recent years, there have also been reported the development of polymers for achieving long-lasting release intended for topical applications, long-lasting films and containers for releasing the drug quantitatively by release from one side; in any case, however, they have disadvantages that high levels of techniques and equipment are required and that the form of that device (preparation) is retained even in the vital body (administration site) to give an extraneous feel to the human. Further, they also have such disadvantages that the expected drug efficacy is difficult to obtain because the stability of the active ingredient is adversely affected, the biological availability is low and the like.